NATIONAL

VARIAN ~ ITS ~ RICHARDSON

National is the house brand of Richardson Electronics, one of today's major tube suppliers. Looking from your left to right, you can follow the name's progression from Varian's ownership, through an
outfit named Industrial Tube Specialists. Based on the logo, it appears the last two boxes are under Richardson's ownership of the name.

The tube writing color is blue on the Varian and ITS tubes and red on the other versions. The Varian and ITS tubes use the year-week date format. Some of the red tubes use the same date code and some
have no date code. None have an EIA/RETMA manufacturers code.